【作者】 冯强；

【导师】 吴博达；

【作者基本信息】 吉林大学 ， 机械制造及自动化， 2004， 硕士

【摘要】 由于压电体具有反应速度快、变形精度高的特点，因而成为近年来构造精密驱动装置的主要方式。通过同传统的精密驱动机构比较和分析，认为压电材料在实现精密驱动上具有相当大的优势。对精密驱动技术在当前的主要运用领域、精密驱动技术的主要类型及特点、驱动材料、等现状进行了综述。分析了目前国内外压电型精密驱动的实现形式及存在的问题。压电驱动基础理论压电驱动的基础是压电效应和逆压电效应。 衡量压电陶瓷性能的因素有机电耦合系数K、机械品质因数Qm、相对介电常数(、弹性常数s、压电常数d、工作条件参数等。压电材料作为一种具有压电效应的弹性体，其在电场中的电行为可以用电场强度E和电位移D两个电学量来描述。对于一块不受外力作用的电介质，在外电场中，其电场强度和电位移的关系为：D=εE 其中，ε是电介质常数，其单位是法拉／米。压电驱动技术是压电学在机械领域中的延伸与发展，目前比较成熟的运用有：压电超声波马达、流体驱动与控制机构、精密驱动机构。常用的压电驱动器有叠层型压电陶瓷和压电双晶片型压电陶瓷。本文利用压电双晶片作为驱动源，介绍了其支撑形式、电气连接形式及其特性的一<WP=86>般规律。对机构基本构成部分之一的柔性铰链顺便作了简单的介绍。机构运动原理及理论分析利用压电双晶片作为驱动源，本文设计了三种精密驱动器，分别是单自由度平动驱动器、x-y两自由度平动驱动器及x-y两自由度摆动驱动器。分别详细介绍了三种机构的选用材料、结构、工作原理及加工方法。对驱动器的重要组成部分柔性铰链作了介绍，其中本文所设计的机构中涉及两种柔性铰链，一种是圆弧摆动柔性铰链，另一种为平行板移动副式柔性铰链，从微位移机构的实际情况出发，对两种柔性铰链分别作了理论分析。对于圆弧摆动柔性铰链，它应用于x-y两自由度摆动机构中，根据精密驱动器位移较小的特点，对其建立理论模型，推导了简化设计方法：得到柔性铰链转角公式： = 相应地，可得到其转角刚度公式： 在柔性铰链的设计中，最关键的是转角刚度设计计算。由分析可以得知：单轴柔性铰链转角刚度与材料弹性模量、铰链宽度、铰链园弧半径以及铰链的最小厚度有关，其中材料弹性模量在材料选定之后就已经确定了，然后根据柔性铰链机械传动部件整体尺寸的要求确定铰链的宽度，接下来就要进行单轴柔性铰链圆弧半径与最小厚度的选择。 通过分析柔性铰链转角公式及刚度公式得知，单轴柔性铰链的最小厚度的变化对铰链特性影响最显著，而铰链圆弧半径相对影响较小。由转角刚度公式可以知道， 铰链最小厚度与转角刚度成正比，铰链圆弧半径则与之成反比。因此，在柔性铰链机械传动部件设计中，要确保良好的动态特性和抗干扰性能，应尽可能地增大柔性铰链的最小厚度，并减小其圆弧半径。 <WP=87>对于平行板移动副式柔性铰链，由于结构的对称性, 中部正方体只发生平动而不转动，因此可以进行简化建模，由于精密驱动器位移较小，可以认为铰链的支撑壁只是发生弯曲变形，通过材料力学中的莫尔积分式求得弹性平板的刚度 对于三种机构中的柔性铰链，应用了CATIA软件分析模块中的有限元分析，结果与解析式计算及实验测得数据相符。通过弹性平板的刚度公式和实验所测得的平板的变形，还可以反推出双端固支式压电双晶片的近似输出力。对于压电双晶片而言，要想将它用到具体的机构上还需要对它做些具体的结构上的改动，本文就采用在压电双晶片中间打孔然后串连接轴的方法，通过有限元的分析，压电双晶片在打孔前后性能没有什么变化，因此可以在机构中使用。精密驱动器的实验研究在实验室内本人实际动手设计并制造了三种精密驱动机构的样机，并进行了相关的试验研究。通过实验具体研究了精密驱动机构的工作性能同各种参数的关系，如压电双晶片铍青铜和压电陶瓷片厚度尺寸搭配、分别加单方向电压及不同方向电压机构的滞环、机构的蠕变特性、机构的重复定位精度等。通过理论分析和实验测试，得出如下结论：1、对于不同厚度尺寸下压电双晶片铍青铜和压电陶瓷片的搭配，为了同时获得压电双晶片有较大的输出变形及较大的输出力，应选择0.40mm 厚的铍青铜和0.35mm厚的压电陶瓷片组合。2、通过实验验证了压电双晶片型能在打孔前后性能几乎没有什么变化，验证了机构使用打孔双晶片的可行性。3、机构的变形量与电压基本呈线性关系，压电片的滞环效应明显，单向电压驱动时机构的滞环要小于双向电压驱动时的滞环。另外，通过实验数据可看出，用双片驱动时的变形量要远远大于用单片驱动时的变形量，但变形<WP=88>量并不等于分别用单片驱动时的变形量之和，机构对负载的变化反应不明显，有负载时的变形量小于空载时的变形量。4、对机构加单向电压时，饱和电压越大，滞环越大。5、机构的蠕变特性较好，但是操作时间越长，蠕变所产生的变形量的飘移越大。更多还原

【Abstract】 Chapter 1 Introduction Piezoelectric has a great advantage over other material in precision driving field for its quick and precise response.Comparing with the traditional precision actuator, Piezoelectric has become a new way to fulfill precision actuation recently. The paper summarize the current using field, the types and characteristics of precision driving technology, and sum up the driving materials and status of it. The paper also analyzed the international piezoelectric driving methods and questions existing at present.Chapter 2 The basic theories of piezoelectric driving The piezoelectric drive fundamental principles are piezoelectric effect and converse piezoelectric effect. The factors which influence performance include dielectric constant (、elastic constant S 、piezoelectric constant d 、electromechanically coupled coefficients 、mechanical quality factor ,etc. Piezoelectric material is a kind of elastic solids and its electric characterization can be described by electric field intensity E and electric displacement D. for a dielectric free from external force in electric field, the relation between electric <WP=90>field intensity and electric displacement is: D=εE Piezoelectric driving technology is the extension and development of Piezoelectric in mechanics, which has been successfully applied to: ultrasonic motor, fluid driving and control mechanism, precision driving mechanism.The common piezoelectric actuator has two kinds: piezoelectric stocks and. The paper made with piezoelectric bimorph as drive mechanism and introduced its supporting method, electric-connect method and some common principles of its characteristics.Chapter 3 Moving theories and analyses of theories of the mechanism Make use of the piezoelectric bimorph as driving source, this paper designed three kinds of precision actuator, respectively is the single-DOF actuator to move even, x- y two- DOF actuator to move even and x- y two-DOF actuator to move swing. The paper introduces detailed three kinds of actuators about their material, construction, working principle and processing method.Two kinds of flexible hinge, which is the most important part of the actuator, are involved in this paper, one kind is arc-swing flexible hinge, the other is parallel-move flexible hinge, set out from an actual circumstance for micro-displacement mechanism, and the paper made the theories analysis respectively to two kinds of flexible hinges.Arc-swing flexible hinges, is used in the mechanism of x- y two-DOF actuator to move swing, according to the characteristic of micro-displacement of precision actuator, the theories model is established, and deduce the simplifying method of design; the formula of the angle of flexible hinges is gotten: <WP=91>correspondingly, the formula of rigidity is gotten:In the design of the flexible hinges, the calculation of rigidity is the most important. From analysis we can get: the rigidity of flexible hinges is relative to elastic modulus E of material, the width b of hinges, the radius r of hinges and the minimum thickness t. The elastic modulus of material is fixed after a material has been chosen. Then the width t of the hinges is made certain according to the integer size of the transport part belong to the mechanism, in the end, we should choose the radius of hinges and the minimum thickness.After having anal sized the formula of angle and rigidity, we know that the variety of the minimum thickness of hinges influence the characteristic mostly, whereas the variety of radius of hinges influence the characteristic little. From the formula of rigidity we can know, the relationship between the minimum thickness of hinges and the rigidity is direct ratio, the relationship between the radius of hinges and rigidity is inverse ratio. So, in the design process of transporting part of flexible hinges, the minimum thickness of hinges should be increase as much as we can and decrease the radius of hinges at the same time in order to insure its good更多还原